The present disclosure relates to the manufacture of electric machines, such as a motor or generator, and in particular to a machine that automates wire winding of a stator.
One common type of electric machine is a brushless Direct Current (DC) motor that includes two major elements, a stator and a rotor. The stator typically includes a wire coil having a number of windings. The rotor typically includes permanent magnets. The rotor and stator are arranged such that the rotor can move freely with respect to the mechanically fixed stator. As a result, electromagnetic interaction between the stator and the rotor causes the rotor to move in response to polarity changes in the stator windings.
One common design has the rotor embedded as a shaft that turns inside a cylindrical stator. The rotor assembly typically includes a number of permanent magnets placed about a shaft. The magnets are held on the shaft by an outer sleeve. The rotor assembly is rotatively supported within the cylindrical stator housing via low friction bearings.
The stator is often made by laminating a number of disks formed of a ferrous material to form a “back iron.” The disks typically have a center hole with tines formed therein. The laminated stack of disks provides a set of axial slots around which are wrapped copper wire strands to form the motor windings.
It can be appreciated that much of the cost to manufacture an inside wound motor is due to the need to wrap wires around and/or within the axial slots of the stator.
A number of somewhat elaborate machines have been devised to automatically wind a stator. In one common approach, windings are formed by a head that comprises a hollow needle through which a wire strand slides. The needle is supported and controlled by an apparatus to reciprocate within and parallel to the axis of the stator. The needle is thus caused to move about the slots, following a substantially elliptical path. The winding needle(s) are operated by a complex series of mechanical drives and gears to follow the required path. See the machines shown in U.S. Pat. No. 6,032,897 and U.S. Pat. No. 4,817,256, which are herein incorporated by reference in its entirety.
In an approach described in U.S. Pat. No. 5,025,997, which is herein incorporated by reference in its entirety, the stator is held within a fixture such that it can be rotated through a predetermined angle. A wire stopper is attached to one or more ends of the stator. The wire guiding member is slidably supported by a pair of bearings, and driven by a mechanism, so that it is moved periodically through the central hole of the stator, external of the wire stoppers. This winding apparatus requires various components including a stationary frame, a moveable frame, several wire feeding/carrying means, and a wire guiding member fixed to the stationary frame.